CSF Apple Stage / Freeze Damage Probability


While climate change is causing frosts and freezes to be less severe, spring frosts and freezes are not receding as quickly as flowering is advancing, resulting in increased risk for damaging cold snaps. This tool, explained below, is designed to give you a graphical view of your freeze risk based on 50% damage temperature, for a variety of apple cultivars.

Please also take our brief survey to give us feedback on the CSF Apple Freeze Risk Tool.

How do I use this tool?

1. Select your location by inputting your county, state, zip code, or address after clicking on the “Change Location” field, or by navigating to your desired spot on the pop-up map, after clicking “save and select location”
2. Use the control panel on the left to input your date of interest, which will center the graph output on this date, with a window of 30 days surrounding it.
3. Use the control panel on the left to choose your apple cultivar – the graph will automatically update depending on your choice for every parameter.
4. Once all your information is chosen, view the graph output
5. Toggle between “Full Season” and “30-Day Trend” graphs


As you have seen, after you have set your apple variety and location, the graph on the right will automatically update with the 50% damage temperature corresponding to your specific variety, and the observed daily minimum temperature observed at your selected location. If the blue minimum temperature crosses into the orange 50% damage line, your crop is at risk for freeze damage and you should take proper precautions. Expected 50% damage temperature and minimum temperatures are also shown into the future based on weather forecasts to help you anticipate potentially damaging periods.  Hovering over the graph on a particular day allows you to see the values associated with each specific date. You can also toggle between “Full Season” and “30-Day” trend as described in the bullet points.

How does this tool work?

This tool graphs 50% damage temperature versus observed temperature for a several varieties, over a specific date range. It also estimates the stage of development.

Producers can use this tool to:

 Determine the level of frost injury to crops due to sub-freezing temperatures
 Monitor the level of freeze tolerance of crops through time
 Track the phenological stage of development

How is our Apple Freeze Risk Tool unique?

Other frost risk websites refer the user to use Growing Degree Day (GDD) tools, and are not crop or variety-specific. Our tool takes into account damage levels of different crop varieties and plots it against projected and observed minimum and maximum temperature.